Effects of Supplementation of Rice Bran and Roasted Soybean in the Diet on Physico-chemical and Sensory Characteristics of M. longissimus dorsi of Hanwoo Steers

We investigated melting points and sensory characteristics by adding rice bran and roasted soybean to the finishing diet of Hanwoo steers. Thirty-six Hanwoo steers (average age, 20.92 mon-old; average weight, 599.89 kg) were assigned to either Control, Treatment 1 (rice bran) or Treatment 2 (roasted soybean) groups (12 steers/group), considering body weight and age. Supplementation levels of rice bran and roasted soybean were determined to meet total 5% crude fat in the concentrates, and the experimental animals were fed for 314 d until they reached 31.2 mon old. No significant differences were found in the moisture and crude fat content among groups. Melting points of lipid extracted from M longissimus dorsi, subcutaneous fat, and perirenal fats were 25.83-26.17, 17.26-18.53 and 32.40-33.15 degrees C, respectively, resulting in remarkable differences depending on fat depots. Contents of free amino acids in M longissimus dorsi related to sweet taste were 39.48 mull 00 g for Treatment 1, which was significantly (p<0.05) higher than those for Control (32.24 mg/100 g), whereas those related to bitter taste were 25.93 mg/100 g for Treatment 2, which was the lowest (p<0.05) among the groups. Fatty acid composition, such as C-14:0, C-16:0, C-16:1, C-18:0, and C-18:1, in M longissimus dorsi was not different among the groups. Results of a panel test on M. longissimus dorsi showed that Treatment 1 scored the highest (p<0.05) in juiciness, and both Treatments 1 and 2 scored higher (p<0.05) in overall palatability than the Control group. C18:1 showed a positive (+) relationship with tenderness (r = 0.650; p<0.05), and C-18:0 with flavor (0.698; p<0.05). The results suggest that rice bran and roasted soybean are beneficial for improving M longissimus dorsi sensory characteristics, whereas no significant differences were found in the physico-chemical characteristics among the groups.